Internal-combustion engine



Oct. 22, 1929. GARUFFA INTERNAL COMBUSTION ENGINE Filed Jan. 22, 1926atented Oct. 22, 1929 um'r so STATES EGIDIO GABUFFA, OF MILAN, ITALYETERNAL-COMBUSTION Enema Application liled January 22,1926, Serial:li'o. 82,952, and in Italy January 23, 1925.

The present invention relates to internal combustion engines and moreparticularly to a two-cycle engine.

While the present invention may be used ti tor other purposes, it isparticularly adapted tor air-craft engines where the weight of an engineis of particular importance. In such uses, a two-cycle engine ispreferred on account of its low weight per horse power Heretoiore,four-cycle engines have been employed in spite of the extra weight dueto the tact that previous two-cycle engines have not been sucientlydependable to warrant their adoption. Further, in two-cycle enlll gines,the scavenging is not thorough and there is considerable waste of gas inthe oper ation. These and other obstacles render the usual type of suchengine much less desirable than the iour cycle engines.

The present invention overcomes these difticulties by providing a sourcet compressed air for thoroughly scavenging the cylinder and anindependent source of compressed air adapted to be saturated withgasoline which will is iorced into the cylinder subsequent to thescavenging operation and slightly prior to the closing oi the exhaustport. Tn this way there is no waste oi" fuel; at the same time thescavenging may be as thorough as desired iii A suitable blower or tanhaving a plurality oi stages may be utilized so that the number ofstages may be changed as the altitude in creases whereby a substantiallyconstant pressure may be maintained in the air and fuel 35 mixturesupplied to the cylinders. In this manner the power of the engineremains constant and its operation is not affected by the varyingchanges in height and the correspond ing changes in the density of theatmosphere.

An object of the present invention is to provide a compact motorparticularly suited tor air-craft uses which has a high volumetricthermal ei'ficiency and capable of maintaining a constant output at highaltitudes.

Another object of theinvention is to provide a thorough scavenging oftwo-cycle engines without waste of fuel and to supply to the enginesubstantially constant quantities oi iuel irrespective of-the density ofthe at- W mosphere.

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Another object of the invention is to rovide an inexpensive aircraftmotor whic is simple in construction and effective in operation and notsubject to breakdowns.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrated embodiment about to be described; andvarious advantages not referred to herein will occur to one skilled inthe art upon employment of the invention in practice.

. ig. 1 is a sectional view through one cylinder of the motor showingthe arrangement of the scavenging and exhaust ports;

Fig. 2 is a work diagram illustrating the opening and closing of thevarious ports;

Fig. 3 is a diagrammatic illustration of the compressed air and fuelmixture supply systems;

Fig. 4 is a side elevational view partly diagrammatic of a motorembodying the present invention; and

Fig. 5 is a diagrammaticillustration of a gas turbine for operating theblower or fan.

Referring to the drawings and more par ticularly to Fig. 1, there isshown a cylinder U having an exhaust port a and scavenging ports a andh. The ports a and h are posi tioned so that the port 6 is slightlyhigher than the exhaust port 8. That is, the piston uncovers the portprior to the exhaust port on its downward strolre and closes the exhaustport prior'to the closing of the port 5 on its compression stroke. Thelower port a of each cylinder is fed with compressed air supplied by asuitable fan or blower at a predetermined pressure. The pressure tube Taconnected to the fan or blower Q, may be used for this purpose. Theupper port I) is fed with a rich fuel mixture which may be air andgasoline under the control of a distributor which is preferably a rotaryone as shown at V. The distributor opens and closes the tube Tb leadingto the port h in timed relation with the movement of the piston.

The two tubes Ta and Tb may be. fed by a single fan or blower 9, itbeing understood that a suitable fuel mixture is injected into the tubeTb. During the downward stroke of the piston the tube Tb isclosed by thedistributor V. As the exhaust port 8 is uncov- Bill ered air is admittedunder pressure through the tube Ta and exhaust port a which scavengesthe cylinder thoroughly due to the shape of the piston head. Theirregular shape of the piston deflects the air toward the head of thecylinder and forces out the burnt gases. Since there is no fuel beingdelivered to the cylinder at this time, an escape of the compressed airthrough the exhaust port 1s unimportant, therefore all of the exhaustgases may be removed without waste of fuel. As the piston reaches theend of its stroke and begins its compression stroke, the distributor Vadmits a rich fuel mixture into the cylinder .just prior to the closingof the exhaust port and continues for a short time after the exhaustport a and port a are closed. In this way any desired fuel charge may besupplied without waste.

The work diagram of this operation is shown in Fig. 2; The circle havingits center at 0, represents the path of the crank and its verticaldiameter M represents the stroke of the iston. During the stroke portionAB, the port 6 is closed by the distributor which feeds the cylinderwith fuel. During the portion B-C compressed air is sup lied throughport a and during portion O the exhaust portion 8 is open. By drawing ahorizontal line through the points A, B, C D and E, the total height hof the supply and scavenging ports and the total height h of the exhaustports are obtained. The point A is considerably above the point D,representing the closing of the fuel port 6 and exhaust ports,respect1vely. During the down stroke of the piston, the port I; isclosed and no fuel enters the cylinder. When the piston reaches the lineD-D the exhaust port is open and the exhaust continues through the angleDOD while air is supplied during the period represented by the angleBOBK By means of the distributor V controlling the fuel port I).

the admission of air and gasoline begins at the point F and continuesthrough the stroke represented by the angle FOA. In this manner theinitial scavenging is efiected with air only and leakage is of littleimportance. The mixture is introduced shortly before the exhaust portcloses and continues for a short period after the closing. The fuelsupply and the scavenging being effected by two independent gaseouscurrents of different qualities produces the best conditions forobtaining complete scavenging and prevents loss of fuel through theexhaust port. It permits complete elimination of smoke and the completefilling of the combustion chamber with the fuel mixture.

While any type of fan or blower may be used the preferred embodimentcontem lates a turbo-compressor operated by a suitable motor or by anexhaust gas turbine as shown in Fig. 3. The blower may be connectedthrough the engine crank shaft 0+0 through the pinion R on the shaft XXof the blower in any suitable manner.

Preferably the turbo blower has four stages (I-IV) and can deliver thequantity of air necessary for scavenging the cylinder at a predeterminedpressure. The rotation of the blower may be effected by the turbine Toperated by the exhaust gases. In order to prevent too great an angularvelocity the turbine is of a two-stage construction. It receives theexhaust gases from the engine through the exhaust pipe 8 and dischargesthe gas at S Since the blower is also connected to the engine throughcrank shaft OO, two separate drives are provided and a suitable clutch Ipermits the blower to 'be driven directly by the engine through thepinion R when desired. Accordingly if the turbine T fails to functionthe blower may be driven by the englue or if greater power is desiredthan afforded by the turbine T, both the turbine and the engine may beused or the engine alone.

In order to obtain constant power at diiferent. hei hts, it is desirablethat the engine should e fed with a constant weight of air and also witha constant weight of gasoline. The present blower accomplishes this byhaving the valves Z and Z While flying at considerable altitudes the airmay be taken from the fourth stage through valve Z which increases thepressure. The volume may be increased simultaneously through the speedchange gear on shaft X-X,which preferably permits the blower to operateat three different angular speeds, M, n, n.

As volumes and pressures are nearly related to square of annular speedsboth will increase, passing from n to n according to the relation andpassing from n to n according to relation Increasing the volume andpressure also increases the power required to operate the blower; butthe discharging exhaust gases possess the necessary energy and in anyevent direct coupling with the engine can be used if desired.

Atomization of the gasoline is effected in the tube Tb by an atomizer Vwhich is adjustable to vary the amount of fuel fed as desired. Gasolineis supplied from a receptacle H through tube 2. Pressure in thisreceptacle is preferably greater than the scavenging pressure so as toobtain very fine atomization which is facilitated by the heat of thecompressed air.

Fuel is supplied to the receptacle H by any suitable means here shown asa pump W.

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pump may be driven either by the en glue or by a small air propeller ifused in aircraft. The tube 2 connects the atomizer V with the lowerportion of the receptacle and a tube 3 is connected to a suitablecompressor which delivers air through the automatic valve y from one ofthe engine cylinders. The automatic valve 4 is adapted to discharge anyexcessive pressure in the receptacle. The tank H is also provided with apet cock 6 for discharging gasoline and a monometer 5.

Une form of engine is shown in Fig. lhaving a motor casing A with-a baseportion B. Six cylinders are shown, 0,, C C C C and C The gas turbine Tis shown at the front end thereof for driving the fan or blower S. Amechanical drive direct from the -engine.is shown through pinion R. The

speed control gear Co and the tubes Ta, Tb are shown connected to therespective cylinders by T branches. The fuel supply tank H and atomizerV are properly connected as described hereinbefore.

In Fig. 5', the gas tubine T is shown arranged adjacent the turbo-blowerS on shaft O-O. The speed control gear Co is mounted on the front end ofthe shaft OO and drives the hollow shaft O,-----O telescoped about theshaft O-O. i

As various changes may be made in the above embodiment without departingfrom the spirit of the invention, it is to be understood that all matterherein set forth is to be interpreted as illustrative and not in alimiting sense. I

Having thus described my invention, I claim:

1. A two-cycle internal combustion engine comprising a plurality ofcylinders, a turboblower having a plurality of stages therein, means forsupplying air from said blower to said cylinders from different stagesof said blower, aridmeans for driving said blower at variable speeds toincrease the volume of air delivered to the cylinders independently ofthe speed of the engine.

2. A two-cycle internal combustion engine comprising a plurality ofcylinders, a turboblower having a plurality of stages therein, means forconducting air from different stages of said blower to said cylindersfor scavenging same, and means for conducting air from said blower to anatomizer for supplying fuel to said engine.

3. A two-cycle combustion engine comprising-a cylinder, a turbo-blowerhaving a plurality of stages therein and means for supplying air fromsaid blower to said cylindcr from different stages of said blower forscavenging same, means for driving said blower at variable speeds toincrease the vol ume of air delivered to the cylinder, and devices forconnecting different stages of said blower with an atomizer forsupplying fuel to the cylinders.

4. Amulti-cylinder engine the combination of air compressing means forsupplying air under pressure to said cylinder, a turbine operated by.the exhaust gases for driving said compressing means, and devices forconnecting said compressing means directly to the engine to be driventhereby.

5. A multi-cylinder engine the combination of a multistage aircompressing means for supplying air under pressure to said cylindersfrom different stages thereof, means operated by the exhaust gases fordriving said compressing means, and a clutch for connecting saidcompressing means directly to the engine to afford greater power for theoperation thereof.

6. A multi-cylinder engine for aeroplanes and the like, the combinationof compressing means for delivering compressed air to said cylinders,devices adapted to be operated by the exhaust gases for driving saidcompressing means, said compressing means being adapted to be drivenalso by the engine, and a mechanism for connecting said means either tosaid engine or to said devices.

In a two-cycle engine of the class described, the combination ofa-distributor for supplying a mixture to said cylinder, a reservoir forliquid fuel and means for maintaining the pressure in said reservoirgreater than the scavenging pressure, said means comprising a connectionwith one of said cylinders to render the explosive pressure effectivethereon.

8. In a two-cycle internal combustion engine, the combination of amultistage compressor for supplying scavenging air to said engine, adistributor for supplying a fuel mixture to said cylinder, a reservoirhaving a supply of liquid fuel, and means for maintaining a pressure insaid reservoir greater than the scavenging pressure in said engine toassure proper operation of said distributor at all times. 7

9. In a two-cycle intepnalcombustion engine, the combinationrof amultistage compressor for supplying scavenging air to said engine, andfor supplying'air to said distributor, a distributor for supplying afuel mixture to said engine, a reservoir for fuel and means connectedwith a cylinder head for maintaining a pressure in said reservoiradequate to supply fuel to said distributor at all pressures to whichthe distributor is subjected.

Signed at Milan, Italy, this 4th day of January, 1926.

EGIDIO GARUFFA.

